1. Field of the Invention
The present invention relates to medical devices used to treat aneurysms within diseased blood vessels, and more particularly, relates to medical devices used to seal the neck of terminal aneurysms which occur in the vicinity of a bifurcated blood vessel.
2. Description of the Prior Art
The use of vascular occlusive medical devices has become a common therapy for the treatment of aneurysms. Aneurysms are often times treated by performing vascular surgery. Vascular surgery allows a physician to access, clip and sometimes remove an aneurysm. This surgical procedure, however, is extremely traumatic and presents a high level of risk, particularly when treating cerebral aneurysms.
To avoid the high risk of vascular surgery, intravascular devices have been used to either cover or fill an aneurysm. For example, grafted stents have been used to cover the neck of an aneurysm and prevent blood flow within the aneurysm. Grafted stents, however, may impede blood flow through blood vessels surrounding the aneurysm. For this reason, grafted stents have limited use in treating aneurysms, particularly terminal aneurysms which occur at or near blood vessel bifurcations.
To fill an aneurysm, various medical devices, such as embolic coils, have been used. Such medical devices are intended to partially fill an aneurysm and promote the formation of thrombus within the aneurysm. The embolic coils and surrounding thrombus prevent further blood flow within the aneurysm and reduce the pressure on the aneurismal wall, thus reducing the risk of rupture. Thrombus within an aneurysm, however, may migrate out of the aneurysm and cause emboli formation downstream, leading to more serious problems, such as ischemic stroke.
An alternative therapy involves placing embolic coils within an aneurysm and supporting the embolic coils within the aneurysm with a stent or other such retaining device. U.S. Pat. No. 6,093,199, entitled “Intra-luminal Device for Treatment of Body Cavities and Lumens and Method of Use,” discloses an intraluminal device comprising a flow retainer for maintaining an embolic mass within an aneurysm and an anchoring element for holding the retainer within a blood vessel. U.S. Pat. No. 6,183,495, entitled “Wire Frame Partial Flow Obstruction Device for Aneurysm Treatment,” discloses a wire-frame stent for use within the vasculature. The stent includes a flow disrupting region disposed between the ends of the stent for restricting the flow of blood into an aneurysm.